TECHNICAL - FREQUENTLY ASKED QUESTIONS
Do you have a minimum wall thickness for each material?
They are mostly similar although Titanium will tend to buckle with thin walls over distance (the distance depends on thickness and shape). The other materials will also do this but to a lesser extent. This is related to the thermal conductivity – Titanium is a poor thermal conductor so suffers most from this. The wall thickness depends on the shape and the part. It is possible to do 0.18mm wall thickness however this is not ideal, 0.3 – 0.5mm is better however these may still buckle depending on shape. The issue is often greatly reduced (fixed) via a lattice structure or a stiffening beam (not big and may be removable).
Should I design solid parts, or can I work with you to create hollowed out structures with lattice infill?
Talk to us about hollow parts and lattice infills and we will advise what is the best option for your part. We encourage complex shapes. We encourage complex shapes, so we do suggest if keeping a part solid, then only keep the material that is needed for the performance and strength of the part. Lattice infill is a very effective method to remove a lot of weight from a part (and often cost if left solid) without the designer needing to create complex and time-consuming pocketing or cavities.
Does a lattice add much cost?
The customer pays for the material used, so while the lattice is not free, it will not add any disproportionate cost to the print, and often can result in a cheaper print due to global weight savings. A lattice part is certainly cheaper than a solid part but more than a completely hollow part.
With the infill, how do I specify its style and density.
The lattice can be made in many structures. Most companies will either say a light, medium or heavy mesh, although this is not very accurate. You could specify the diameter of the strut and we could find the closest structure. Generally we can scale the lattice up or down. The length of the struts is adjustable to create different densities within the same lattice node structure. There could be some variations, so we can work with you on that to get the best outcome.
Remember there will also need to be a couple of small holes in the part to get the powder out so we need to know where we can put these also. Ideally 1 -2mm diameter is best.
What shape is the lattice?
We have several options available as our preferred standard lattices. Our lattice has balanced properties in all directions. We can include customer generated lattice structures.
Can you take a customer’s solid part and determine the wall thickness and lattice?
First, we will seek some guidance from our customer on what they think is a good starting point. We can create the internal cavity and lattice, however, it is the client’s responsibility to ensure the part meets structural needs. We can suggest a minimum wall thickness and minimum lattice member size but the client must approve these. We can send an STL file of the part back to customers for their own FEA review if required.
Can I create variable wall thickness parts – both with and without lattice?
Talk to us about the best way to achieve this.
Do I need a drain hole for internal cavities – if so what size?
Generally a couple of 1 – 2mm holes is perfect but smaller holes can also work.
What affects part distortion – i.e. total size / solid thickness / sudden thickness changes / overhangs that droop?
The most common cause is solid thickness; this is the main issue however sudden changes in thickness or major feature changes can also have an effect. The sudden changes in thickness and feature change tends to be less of a major problem and any will generally result in a cosmetic rather than structural issue. The solid thickness is the main cause of problem especially where it is over a long distance on the x,y plain (the Z is not an issue).
Do you add support structure to prevent part drooping or distortions during the print?
Yes, we take care of this.
Do I need to orient the part in the way it will be printed or does RAM do this?
Yes, we take care of this.
Can you print a thread, or should I print a tapping hole and cut the thread myself?
Yes, we can print a thread, However, in most cases we need to chase the thread with a tap to clean the surface for the best results. We prefer customers to only put a tapping drill hole in their part to let us add the thread feature. This incurs a small extra fee for our additional time, so it is optional if the customer prefers to finish the part themselves.